Integrated optimization and control of an engine and aftertreatment system

ABSTRACT

An engine and one or more aftertreatment subsystems integrated into one system for optimization and control. At least one controller may be connected to the engine and the one or more aftertreatment subsystems. The controller may contain and execute a program for the optimization and control of the one system. Controller may receive information pertinent to the engine and the one or more aftertreatment subsystems for the program. The controller may prescribe setpoints and constraints for measured variables and positions of actuators according to the program to aid in effecting the optimization and control of the one system.

This application is a continuation of U.S. patent application Ser. No.13/290,025, filed Nov. 4, 2011. U.S. patent application Ser. No.13/290,025, filed Nov. 4, 2011, is hereby incorporated by reference.

BACKGROUND

The present disclosure pertains to internal combustion engines andparticularly to engines having aftertreatment mechanisms.

SUMMARY

The disclosure reveals an engine and one or more aftertreatmentsubsystems integrated into one system for optimization and control. Atleast one controller may be connected to the engine and the one or moreaftertreatment subsystems. The controller may contain and execute aprogram for the optimization and control of the one system. Controllermay receive information pertinent to the engine and the one or moreaftertreatment subsystems for the program. The controller may prescribesetpoints and constraints for measured variables and positions ofactuators according to the program to aid in effecting the optimizationand control of the one system.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagram of a basic scheme of the present system forintegrated optimization and control of an engine with one or moreaftertreatment subsystems;

FIG. 2 is a diagram of an illustrative example engine map;

FIG. 3 is a diagram of an illustrative example engine or aftertreatmentsubsystem interconnected with a controller;

FIG. 4 is a diagram of the example in FIG. 3 with an engine and amultiple of aftertreatment subsystems; and

FIG. 5 is a diagram of an illustrative example of an approach for theengine and aftertreatment system.

DESCRIPTION

The modern combustion engine appears to be a very complex system. Thecomplexity growth may be driven namely by governmental legislation thatrestricts combustion engine emissions. Therefore, the original equipmentmanufacturers (OEMs) may be forced to add various equipment items,sensors and actuators to the engine to achieve the prescribed limits andto optimize engine operating costs, e.g., fuel economy, ureaconsumption, and so forth. Under these conditions, an engine operationoptimization and design of an optimal control system may be achallenging task.

Some approaches may incorporate optimizing the engine and individualaftertreatment systems involving, e.g., selective catalytic reduction(SCR), diesel oxidation catalysts (DOC), diesel particulate filter(DPF), and so on, separately. These approaches do not necessarilyprovide a systematic way of optimization. They may involve timeconsuming and expensive tasks. Furthermore, it is not necessarilyensured that their results will be optimal. There might be a bettersolution.

Another approach may be to optimize the engine together with theaftertreatment subsystem (AFS) as a one system. Such an approach mayenable one to find the global optimal behavior of the engine with anaftertreatment subsystem from an economical and technical point of viewwhile satisfying virtually all of the prescribed emission limits. Theengine and aftertreatment subsystem may have appropriate sensors andactuators as needed to effect an optimization program for the engine andaftertreatment subsystem or subsystems as one system. The engine may beseen as an exhaust gas source for the aftertreatment subsystem. Theproperties of the engine out exhaust gas as sensed may be influencedwithin certain range by manipulating available engine actuators such asthose of a turbocharger waste gate (WG), variable geometry turbocharger(VGT), exhaust gas recirculation (EGR), start of injection (SOI),throttling valve (TV), and so on. Various degrees of freedom may be usedto prepare or modify the exhaust gas properties for optimal operation ofthe aftertreatment subsystem at virtually all of the engine operatingpoints. For example, if the actual state of the aftertreatment subsystemdoes not enable a reduction of emissions due to low temperature assensed in some operating regimes, then the engine actuators may becontrolled to increase temperature so that the engine exhaust gas outemissions do not violate prescribed limits. On the other hand, if thestate of the aftertreatment subsystem enables a reduction of asignificant amount of pollutants, the engine actuators may be controlledin a way to also achieve the best fuel economy.

An engine optimization and control design may be formulated as arigorous mathematical optimization problem. The present approach mayoffer a modular and systematic solution to the problem. The approach mayincorporate dividing the engine and aftertreatment optimization andcontrol design into two stages: (i) an off-line part and (ii) an on-linepart (real-time).

(i) The off-line part may be formulated as a mathematical optimizationproblem with constraints (known as mathematical programming) and theresults may be various engine maps prescribing setpoints and constraintsfor different kinds of measured variables from sensors and positions ofvirtually all engine actuators for virtually all major operating pointsor conditions of the engine, e.g., over the engine speed and torque map.Virtually all of the maps may be parameterized by various variables ofthe engine and aftertreatment system but may be also parameterized bymeasured fuel and/or urea consumption and corresponding costs, by theirratio, or other relevant economically related quantities. Informationabout actual market prices of fuel and other fluids used by the engineand aftertreatment system may be incorporated to parameterize thecontrol system and may be used as a tuning parameter during the engine'slifetime. This approach may enable a slight tuning of the controllerbehavior when the prices of the fluids used are changed, which canensure economically optimal operation of the engine in view of suchchanges during its lifetime.

(ii) The on-line part may consist of one or more feedback single ormultivariable real-time controllers. These controllers may beimplemented, for example, as model based predictive controllers (MPCs).The feedback controllers may ensure realization of virtually all of thesetpoints, but also satisfaction of virtually all of the constraintscomputed in the off-line part. The feedback controllers may also ensuredisturbance rejection, a minimization of an impact of engine componentsproduction variability, and aging of the engine. Furthermore, thefeedback controllers may also be designed to deliver needed performanceduring an engine transient operation.

FIG. 1 is a block diagram of a basic scheme of the present system forintegrated optimization and control of an engine with one or moreaftertreatment systems. The various blocks represent an engine 11, andseveral aftertreatment systems (AFSs) 12 and 13. Aftertreatment system13 may be the last system and be denoted by an “N”. “N” may alsoindicate the total number of aftertreatment systems. An aftertreatmentsystem 12 between engine 11 and aftertreatment system N may be denotedby an “i”. There may be any number of aftertreatment systems. If thereis one aftertreatment system, then it may be represented as system N,wherein N=1.

“x₀” within the symbol for engine 11 may indicate an internal state ofthe engine. “x_(i)” and “x_(N)” may indicate internal states of AFSi 12and AFSN 13, respectively. “v₀” may represent an external input 15 toengine 11. The external input may incorporate disturbance, fluid price,and so on. Similarly, “v_(i)” and “v_(N)” may represent external inputs24 and 25 for AFSi 12 and AFSN 13, respectively. A _(“) _(U0)” input 16may represent an actuator or actuators of engine 11, a “u_(i)” input 26may represent an actuator or actuators of AFSi 12, and a “u_(N)” input27 may represent an actuator or actuators of AFSN 13. Inputs 16, 26 and27 may incorporate actuator inputs.

“J₀(x₀,v₀,u₀)” on an output 17 may represent a subsystem cost functionof x₀, v₀ and/or u₀ for engine 11. “g(x₀,v₀,u₀)≤0” also on output 17 mayrepresent subsystem constraints of x₀, v₀ and/or u₀ for engine 11. “y₀”may represent an interconnection output 18 from engine 11 which may bean interconnection input “y_(i−1)” 19 to AFSi 12, assuming that AFSi 12is the first AFS connected to engine 11, where i=1. However, there maybe one or more AFSs connected between engine 11 and AFSi 12. “y_(i)” mayrepresent an interconnection output 21 from AFSi 12 which may be aninterconnection input “y_(N−1)” 22 to AFSN 13, assuming that AFSN 13 isconnected to AFSi 12. However, there may be one or more AFSs connectedbetween AFSi 12 and AFSN 13. “y_(N)” may represent an output 23 of theAFSN 13 and the preceding AFSs from “1” through “N−1”.

“J_(i)(x_(i),v_(i),u_(i),y_(i−1))” on an output 28 may represent asubsystem cost function of x_(i), v_(i), u_(i) and/or y_(i−1) for AFSi12. “J_(i)(.)” may be an abbreviated designation of the subsystem costfunction. “g(x_(i),v_(i),u_(i),y_(i−1))≤0” also on output 28 mayrepresent subsystem constraints of x_(i), v_(i), u_(i) and/or y_(i−1)for AFSi 12. “g(.)” may be an abbreviated designation of the subsystemconstraints. “J_(N)(x_(N),v_(N),u_(N),y_(N−1)” on an output 29 mayrepresent subsystem cost function of x_(N), v_(N), u_(N) and/or y_(N−1)for AFSN 13. “g(x_(N),v_(N),u_(N),y_(N−1))≤0” also on output 29 mayrepresent subsystem constraints of x_(N), v_(N), u_(N) and/or y_(N−1)for AFSN 13. The similar designations may be made for additional AFSs,if any, between engine 11 and AFSi 12 and between AFSi 12 and AFSN 13,as done herein with the xs, vs, us and ys.

FIG. 2 may aid in illustrating off-line optimization. An objective maybe to compute optimal steady-state engine maps for virtually all of theoperating points, for example, in an engine speed-torque space as shownwith a graph 31 of engine torque (nm) versus engine speed (rpm). Graph31 illustrates an example k-th operating point 32 plotted at a specifictorque and engine speed. The k-th operating point may represent anypoint at various locations on graph 31.

An optimization problem in each operating point may be indicated by:

${{\min\limits_{U}\; J} = {\sum\limits_{i = 0}^{N}\; {J_{i}( {x_{i},v_{i},u_{i},y_{i - 1}} )}}};{U = \{ {u_{0},u_{1},\ldots \mspace{14mu},u_{N}} \}}$s.t.  g(x_(i), v_(i), u_(i), y_(i − 1)) ≤ 0; i = 0, 1, …  , N.

The resulting optimal steady-state maps may be indicated by:

u _(i) ^(SS) =f _(u) _(i) (v ₀ , . . . , v _(N)) and

y _(i) ^(SS) =f _(y) _(i) (v ₀ , . . . , v _(N)),

Abbreviated designations of the steady-state map indications may beu_(i) ^(SS)=f_(u) _(i) (.) and y_(i) ^(SS)=f_(y) _(i) (.), respectively.It may be noted that the maps may also be parameterized by x_(i) undercertain conditions.

An on-line part (real-time) for an i-th aftertreatment subsystem or anengine may be illustrated in FIG. 3. A controller may be integrated withan engine and an AFS. An engine or AFS_i 41 may have an internal stateof x₀ or x_(i), respectively. An actuator input u₀ or u_(i) 43 may go tothe engine or AFS_i 41, respectively. The actuator input 43 may comefrom a controller_0 or a controller_i 42, respectively. Controller 42may provide steady state maps as represented by symbols u₀ ^(SS)=f_(u) ₀(.) and y₀ ^(SS)=f_(y) ₀ (.) or u_(i) ^(SS)=f_(u) _(i) (.) and y_(i)^(SS)=f_(y) _(i) (.), respectively. The controller_i 42 may beimplemented by MPC controller. External inputs v₀, . . . , v_(N) (i.e.,disturbance, fluid price, and so forth) may be provided to controller42. A specific input v₀ or v_(i) 45 may be input to engine or AFS_i 41,respectively. An interconnection output y_(i−1) 47 from an engine or anAFS_i−1 may be an input 46 to AFS_i 41 and controller_i 42. There may bean interconnection output y₀ or y_(i) 47 from the engine or AFS_i 41 asan input 46 for an AFS_i+1 or an AFS_N. Interconnection output 47 mayalso go to controller_i 42. In general, 47 may contain also signalswhich are not interconnections but measurements of variables that can beuseful for integrated optimization.

The on-line part for an i-th subsystem of FIG. 3 may be illustrated asan engine and multiple AFSs connected in a diagram of FIG. 4. Two ormore controllers 42 of FIG. 4 may be combined as one controller 42. Thenumerical labels are the same for similar components and lines as shownin FIG. 3.

FIG. 5 is diagram of a two-part engine and aftertreatment optimizationcontrol approach 50 with an off-line stage 51 and an on-line stage 52.At the off-line stage 51 may be a mathematical optimization of theengine and aftertreatment system at symbol 53, an engine map withsetpoints and constraints at symbol 54, and a parameterization of enginemaps at symbol 55. At the on-line stage 52 may be feedback real-timecontroller or controllers at symbol 56, a realization of setpoints atsymbol 57, and a satisfaction of constraints at symbol 58.

Some of the items or activities of the disclosed system in FIGS. 1-5 notcovered by one or more controllers may be performed by aprocessor/computer.

A recap of the disclosure is provided in the following. An engine andaftertreatment system may incorporate an engine, an aftertreatmentmechanism connected to the engine, and a controller connected to theengine and the aftertreatment mechanism. The controller may have anoptimization program. The optimization program may be for optimizedperformance of the engine and the aftertreatment mechanism integrated asone system. Optimized performance may incorporate reducing emissions andincreasing fluid efficiency of the one system.

The optimization program may incorporate the aftertreatment mechanismfor reducing emissions from an exhaust of the engine to a prescribedlevel, and increasing fluid efficiency of the engine and theaftertreatment mechanism while the emissions are reduced at least downto the prescribed level.

The engine may incorporate a control input to actuators on the engine,an interconnection output and an information output. The informationoutput may indicate engine costs and/or engine constraints. Theaftertreatment mechanism may incorporate an interconnection inputconnected to the interconnection output of the engine, a control inputto actuators on the aftertreatment mechanism, an interconnection output,and an information output. The information output may indicateaftertreatment mechanism costs and/or aftertreatment mechanismconstraints. The costs and constraints may be a basis incorporated inthe optimization program for optimized performance of the engine and theaftertreatment mechanism integrated as one system.

The controller may further incorporate a first input connected to theinterconnection output of the engine, a first output connected to thecontrol input to actuators of the engine, a second input connected withthe interconnection input of the aftertreatment mechanism, a third inputconnected to the interconnection output of the aftertreatment mechanism,and a second output connected to the control input to actuators of theaftertreatment mechanism.

The controller may further incorporate a feedback loop for disturbancerejection, minimizing an impact of variability of performance of theengine, and/or delivering predetermined performance of theaftertreatment mechanism during transient operation of the engine, andmaps prescribing setpoints and constraints for measured variables andpositions of engine actuators for one or more operating points of theengine. The maps may be parameterized by variables of the engine and theaftertreatment mechanism. The maps may be a basis incorporated in theoptimization program for optimized performance of the engine and theaftertreatment mechanism integrated as one system.

An approach for engine and aftertreatment optimization and control mayincorporate formulating an off-line part which involves mathematicallyoptimizing an engine and aftertreatment system, providing engine mapsprescribing setpoints and constraints for measured variables fromsensors and positions of engine actuators for operating points andconditions of the engine, and parameterizing the engine maps withvariables of the engine and the aftertreatment system.

The approach for engine and aftertreatment optimization and control mayalso incorporate formulating an on-line part providing one or morefeedback real-time controllers realizing the setpoints of the engine andaftertreatment system, and satisfying computed constraints with the oneor more controllers. The one or more controllers may be model predictivecontrollers.

The one or more controllers may ensure disturbance rejection,minimization of input of engine components production variability,and/or engine aging. The one or more controllers may deliver neededperformance during an engine transient operation.

The approach may further incorporate parameterizing the engine andaftertreatment system by measured fuel, urea consumption and/orcorresponding costs. The approach may also further incorporateparameterizing a control system with market price information of fueland other fluids used by the engine and aftertreatment system. There mayalso be parameterizing the control system to tune the controller whenthere are changes of prices of fluids used by the engine andaftertreatment system to ensure economically optimal operation of theengine during the changes.

There may be a system of an engine and aftertreatment subsystemincorporating an engine, an aftertreatment subsystem connected to theengine, and a controller connected to the engine and the aftertreatmentsubsystem. The controller may receive signals from sensors of the engineand the aftertreatment subsystem, process the signals, and providesignals to actuators of the engine and the aftertreatment subsystemaccording to an optimization program for optimized performance of theengine and the aftertreatment subsystem as one system. The optimizedperformance may incorporate reducing emissions and increasing fluidefficiency of the one system.

The external inputs of the engine and the aftertreatment subsystem maybe connected to the controller. The controller may incorporate enginemaps for operating points of the engine. The maps may be a basis foroptimized performance of the engine and the aftertreatment subsystem asone system. The maps may prescribe setpoints and constraints formeasured variables from the sensors and for actuators.

The engine may incorporate an external input and an actuator input fromthe controller, and an interconnection output connected to thecontroller. The external input may have external information pertinentto the engine.

The aftertreatment subsystem may incorporate an interconnection inputconnected to the interconnection output of the engine and connected tothe controller, an external input, an actuator input from thecontroller, and an interconnection output connected to the controller.The external input may have external information pertinent to theaftertreatment subsystem.

The engine may further incorporate an internal state and an informationoutput. The information output may indicate engine costs as a functionof the engine internal state, the external input and/or the actuatorinput.

The aftertreatment subsystem may further incorporate an internal stateand an information output. The information output may indicateaftertreatment costs as a function of the aftertreatment subsysteminternal state, the external input, actuator input, and/or theinterconnection input.

The information output of the engine may indicate engine constraints asa function of the internal state, the external input and/or the actuatorinput of the engine. The information output of the aftertreatmentsubsystem may indicate aftertreatment constraints as a function of theinternal state, the external input, the actuator input, and/or theinterconnection input of the aftertreatment subsystem. The costs andconstraints may be a basis for optimized performance of the engine andthe aftertreatment subsystem as one system.

An approach for controlling a combined engine and aftertreatment systemmay incorporate providing an engine, adding one or more aftertreatmentsubsystems to result in a combined engine and aftertreatment system,connecting one of the one or more aftertreatment subsystems to anexhaust output of the engine, and manipulating actuators of the engineand the one or more aftertreatment subsystems with one or morecontrollers to change the properties of the exhaust for optimaloperation of the combined engine and aftertreatment system. Optimaloperation may incorporate reduction of emissions and improvement offluid efficiency of the combined engine and aftertreatment system.

To change the properties of the exhaust may incorporate reducing anamount of pollutants in the exhaust to a magnitude equal to or less thana prescribed magnitude. Manipulating the actuators of the engine mayincrease fuel economy of the engine if the one or more aftertreatmentsubsystems reduce an amount of pollutants in the exhaust to a magnitudeequal to or less than the prescribed magnitude.

The approach may further incorporate providing one or more engine mapsas a basis for optimal operation of the combined engine andaftertreatment system, processing the one or more engine mapsprescribing setpoints and/or constraints for measured variables andpositions of the actuators on the engine for operating points and/orconditions of the engine, and parameterizing the engine maps byvariables of the engine and of the one or more aftertreatmentsubsystems.

The approach may further incorporate parameterizing the engine maps bycosts of fuel consumed by the engine and/or urea consumed by the one ormore aftertreatment subsystems. The one or more engine maps mayincorporate a speed and torque map of the engine. The one or morecontrollers may be connected to the engine and the one or moreaftertreatment subsystems of the combined engine and aftertreatmentsystem. The one or more controllers may ensure realization of thesetpoints, and/or ensure satisfaction of the constraints.

In the present specification, some of the matter may be of ahypothetical or prophetic nature although stated in another manner ortense.

Although the present system and/or approach has been described withrespect to at least one illustrative example, many variations andmodifications will become apparent to those skilled in the art uponreading the specification. It is therefore the intention that theappended claims be interpreted as broadly as possible in view of therelated art to include all such variations and modifications.

What is claimed is:
 1. An engine monitoring system comprising: an enginehaving a set of engine actuators, wherein the engine is configured todischarge gas; an aftertreatment system configured to receive thedischarged gas from the engine, reduce a level of pollutants in thedischarged gas below an emission limit, and emit the discharged gas; aset of sensors configured to sense the level of pollutants in theemitted discharged gas; and a controller operatively coupled to theengine and the sensors and configured to: receive the level ofpollutants in the emitted discharged gas from the set of sensors;control the set of engine actuators to raise a temperature of thedischarged gas when the level of pollutants in the emitted dischargedgas is above the emission limit; and control the set of engine actuatorsto maximize a fuel economy of the engine when the level of pollutants inthe emitted discharged gas is below the emission limit.
 2. The enginemonitoring system of claim 1, wherein the controller uses the level ofpollutants in the emitted discharged gas and a set of engine maps todetermine setpoints and constraints for the set of engine actuators tomaximize the fuel economy of the engine.
 3. The engine monitoring systemof claim 2, wherein the set of engine maps includes at least one of anengine speed map and a torque map.
 4. The engine monitoring system ofclaim 2, wherein the controller further uses a consumption of fuel and aconsumption of urea to maximize the fuel economy of the engine.
 5. Theengine monitoring system of claim 2, wherein the controller further usesa market price of fuel to maximize the fuel economy of the engine. 6.The engine monitoring system of claim 2, wherein the controller furtheruses an aging of the set of engine actuators to maximize the fueleconomy of the engine.
 7. The engine monitoring system of claim 1,wherein the set of engine actuators includes at least one of: aturbocharger waste gate (WG); variable geometry turbocharger (VGT);exhaust gas recirculation (EGR); start of injection (SOI); andthrottling valve (TV).
 8. A controller for monitoring an engine systemhaving an aftertreatment system configured to receive gas from an engineof the engine system, reduce a level of pollutants in the gas below anemission limit, and emit the gas, the controller configured to: receivethe level of pollutants in the emitted gas from a set of sensors;control a set of engine actuators of the engine to raise a temperatureof the gas before it is emitted when the level of pollutants in theemitted gas is above the emission limit; and control the set of engineactuators to maximize a fuel economy of the engine when the level ofpollutants in the emitted gas is below the emission limit.
 9. Thecontroller of claim 8, wherein the controller uses the level ofpollutants in the emitted gas and a set of engine maps to determinesetpoints and constraints for the set of engine actuators to maximizethe fuel economy of the engine.
 10. The controller of claim 9, whereinthe set of engine maps includes at least one of an engine speed map anda torque map.
 11. The controller of claim 9, wherein the controllerfurther uses a consumption of fuel and a consumption of urea to maximizethe fuel economy of the engine.
 12. The controller of claim 9, whereinthe controller further uses a market price of fuel to maximize the fueleconomy of the engine.
 13. The controller of claim 9, wherein thecontroller further uses an aging of the set of engine actuators tomaximize the fuel economy of the engine.
 14. The controller of claim 8,wherein the set of engine actuators includes at least one of: aturbocharger waste gate (WG); variable geometry turbocharger (VGT);exhaust gas recirculation (EGR); start of injection (SOI); andthrottling valve (TV).
 15. A method for monitoring an engine systemhaving an aftertreatment system configured to receive gas from an engineof the engine system, reduce a level of pollutants in the gas below anemission limit, and emit the gas, the method comprising: receiving thelevel of pollutants in the emitted gas from a set of sensors;controlling a set of engine actuators of the engine to raise atemperature of the gas before it is emitted when the level of pollutantsin the emitted gas is above the emission limit; and controlling the setof engine actuators to maximize a fuel economy of the engine when thelevel of pollutants in the emitted gas is below the emission limit. 16.The method of claim 15, wherein the level of pollutants in the emittedgas and a set of engine maps are used to determine setpoints andconstraints for the set of engine actuators to maximize the fuel economyof the engine.
 17. The method of claim 16, wherein the set of enginemaps includes at least one of an engine speed map and a torque map. 18.The method of claim 16, wherein a consumption of fuel and a consumptionof urea are used to maximize the fuel economy of the engine.
 19. Themethod of claim 16, wherein a market price of fuel is used to maximizethe fuel economy of the engine.
 20. The method of claim 15, wherein theset of engine actuators includes at least one of: a turbocharger wastegate (WG); variable geometry turbocharger (VGT); exhaust gasrecirculation (EGR); start of injection (SOI); and throttling valve(TV).